With progresses in semiconductors and liquid crystal industries, more advanced and efficient carriage systems are requested which can convey processing targets more quickly to target stations.
The Japanese Patent No. 3508130 has been proposed which is intended to meet the above requirement.
In this carriage system, carriages can run between intrabays (in the Japanese Patent No. 3508130, running loops 20 to 25) and interbays (in the Japanese Patent No. 3508130, running loops 2 and 3) which are otherwise composed of closed conveying paths so that processing targets are transferred between the intrabays and interbays via transfer warehouses (in the Japanese Patent No. 3508130, stockers). This carriage system eliminates the need for the transfer of processing targets via the transfer warehouses to increase conveyance speed. The carriage system also enables a reduction in system costs by eliminating the need for the transfer warehouses.
However, in this carriage system, in which the large number of carriages run among the plurality of bays (loops), one of a plurality of running routes must be chosen. The congestion statuses of the running routes thus need to be appropriately determined to select one of them through which the carriage can reach the target station earliest. However, this carriage system does not take this into account.
The present invention solves the above problem. An object of the present invention is to provide a carriage system which, to choose one of a plurality of running routes, can appropriately determine the congestion statuses of the running routes to choose one of them along which a carriage can reach its destination earliest.